Carburetor



E. THUMMEL CARBURETOR July 10, 1956 2 Sheets-Sheet 1 Filed Sept. 16, 1953 INVENTOP sV-WL m a E. THUMMEL July 10, 1956 CARBURETOR 2 Sheets-Sheet 2 Filed Sept. 16, 1953 I'NVENTOR ERICH THUMMEL BY [outlaw United States Patent fice CARBURETOR Erich Thiimmel, Neckarsulm, Germany Application September 16, 1953, Serial No. 380,390 1 Claim. (Cl. 261-44) This invention relates to carburetors for gasoline engines of the Otto type.

It is an object of this invention to provide a carburetor organized for a uniform formation of the fuel and air mixture ranging from idling to full power and for a great saving of fuel consumption, and being of particularly simple design and therefore being secured against excessive wear of its constituent parts.

The carburetors of the kind hitherto in use which are provided with a float tank and an atomizer nozzle moving in the air current in such manner that this nozzle is set according to the value of the suction for the mixture of fuel and air and the admission of air is controlled with the movement of the float tank for the correct fuel consumption, involve the drawback that the movable and sliding parts are subject to considerable wear and their manufacture is costly. The parts worn down do not shut off the control ducts and cause disturbances in the upper numbers of revolution. The long borings of the mixing nozzle cause a slow transmission from one to another number of revolutions and this renders it difficult to speedily increase the speed.

In contrast to these carburetors the device according to this invention comprises a float tank rigidly mounted in a carburetor casing arranged in series with a shutter having the form of a slide which opens and closes the intake opening, being for instance actuated by means of a Bowden train. The atomizer nozzle may be housed in a well known manner in the cover instance, when the flap is open, the atomizing nozzle may be located near the border of the intake opening.

According to this invention, now, there is arranged near the tip of this nozzle a deflecting surface serving to control the air current. This surface may be fixed to the float tank a short distance from the nozzle so as to enable the shutter to move without friction between the tank and the deflecting surface. When the shutter is in closing position, it leaves an air gap open between the tank and the deflecting surface,'and the suction is reduced to a minimum. When the shutter is opened, the air gap will close up in proportion and the air current then will travel more and more across the deflecting surface and will increase in a uniform manner the suction near the atomizing nozzle.

The nozzle system serving for providing the mixture of fuel and air can be mounted in a well known manner in the float tank cover. The main fuel nozzle preferably extends at an angle to the atomizing nozzle in order to shorten the suction distance.

The new carburetor can be dismantled without the use of tools. It is particularly unsensitive against disturbances and has a long life.

In the drawings aflixed to this specification and forming part thereof an embodiment of this invention is illustrated diagrammatically by way of example.

In the drawings:

Fig. 1 is a schematic longitudinal section, while of the float tank. For

Fig. 2 is a vertical cross-section through the starting and final control system.

Fig. 3 is a vertical cross-section showing the parts of the carburetor in the position they occupy during idling of the engine.

Fig. 4 is a similar view showing the shutter, which governs the formation of the fuel and air mixture in the nozzle and the entrance of the mixture into the mixture passage leading to the engine, in an intermediate position, and

Fig. 5 illustrates the position of the parts during the period where the suction acting on this mixture passage acts directly on the fuel in the float tank.

Referring to the drawings, 1 is the streamlined carburetor casing, 2 is the float tank, 3 is the tank cover inserted in the tank with a tight fit and 4 is the carburetor nozzle threaded and screwed into the cover and facing the intake opening 5 leading to the motor. 6 is the shutter having the form of a flap pivoted to the cover 3 and arranged to close the intake opening and provided with an aperture 7 of the size of the opening 5 and with a small slot 12 which, when the shutter is closed during idling, allows a small quantity of fuel and air mixture to pass through to the motor. 8 is a 'throttling surface fixed for instance to the float tank 2 and located in so close proximity to the shutter 6 that this latter can just pass through Without friction between the surface 8 and the carburetor casing 1. When the shutter 6 controlled by a Bowden train (not shown), closes the intake opening 5, the aperture 7 of the flap will leave open a gap 12 between the casing 1 and the throttling surface 8, through which air can flow into the intake opening and reduce the suction acting on the atomizing nozzle 4. If the shutter 6 is opened, the air gap will be closed in proportion and the current of air will gradually be conducted into closer proximity with the atomizing nozzle, until, with a complete uncovering of the opening 5, a maximum suction is exerted at the nozzle. This arrangement renders it possible to maintain at the atomizing nozzle 21 gradually rising vacuum and thereby control the mixture of fuel and air in the most perfect manner.

The atomizing nozzle 4 is in communication, by way of a conduit 9 (Fig. 2) with the head 10 of the nozzle, into which projects the main fuel nozzle 11. This main fuel nozzle is fixed by screwing in the cover 3 of the float tank at an angle to the atomizing nozzle 4 and leads through the conduit 9 towards the nozzle head. The tubular extension 13 of the nozzle which projects into the tank 2, feeds the fuel to the nozzle. In the conduit 9 ends the air conduit 14 (Fig. 2) which starts on the surface of the tank cover 3. The arm 16 of the shutter 6, extending beyond the pivot point 15 of the shutter, controls the admission of additional air by way of the conduit 14.

When the shutter 6 is opened to start the motor, the conduit 14 is gradually closed, the suction at the mouth of the atomizing nozzle gradually nearing the deflecting surface 8 and the fuel and air mixture is enriched accordingly.

In this manner the motor is fed at each number of revolutions, a constant mixture of fuel and air corresponding to this number.

In view of the close arrangement of the conduits a uniform transition from one number of revolutions to the other is obtained. In order to facilitate starting of the motor, a tickler 17 surrounded by a piston-like packing 18 allows the float tank to be shut 01f by pressing down the pin 17 and seal off the vent 19. The air entering the float tank 2 forces down the float by means of the extension 20, thereby causing fresh fuel to enter the tank and raising the pressure which forces the fuel through the main fuel nozzle 11 into the nozzle head 10.

Patented July 10, 1956' This arrangement allows the motor to start at once even at very low temperature, because the fuel is positively mixed with air and atomized.

The carburetor casing 1 is closed in a well known manner by a cover 21 which also supports the float tank, and in this cover a filter 22 is arranged.

The cover can be taken off by loosing two springs and the entire float tank can then be removed and cleaned without a tool being needed.

Referring more especially to Fig. 3, the shutter 6 in its lowermost position presents to the mouth of the conduit 9 of the jet nozzle 4 the narrow gap 12 through which the jet can enter the mixture passage 5, but no suction of an ejector-like action is exerted on the mouth of the nozzle. In this position of the shutter its lowermost portion 25 has sunk below the channel-like gap 26 between the wall of the casing 1 and the throttling member 8 and the aperture 7 in the shutter now allows the full suction effect created by the piston (not shown) of the engine to draw air through the filter 22 and the interior of the casing to pass around the jet nozzle. Since at the same time the arm 16 of the shutter has uncovered the conduit 14, supplementary air can now enter through this conduit into the casing and reach the nozzle conduit in passing through the head 18 of the fuel nozzle and carrying fuel along under the action of the partial vacuum created by the engine piston, so that the fuel and air mixture passes into the cylinder (not shown) of the engine in finely atomized condition.

In proportion to the partial or total uncovering of the conduit 14 more or less air enters the carburetor and carries along more or less fuel.

Fig. 4 shows the active parts of the carburetor in the position where the shutter 6 in an intermediate position obstructs by way of its lowermost portion 25 almost all of the gap between the casing wall and the throttling member 8. A major part of the air passes through the aperture 7 above the mouth 4 of the jet nozzle and a stronger suction effect is exerted on the carburetor, but with the conduit 14 for the supplementary air partly closed the suction in the fuel conduit 13 increases.

When the shutter is raised altogether, as shown in Fig. 5, its lowermost portion 25 closes the gap 26 between the carburetor casing 1 and the throttling member 8. In this position of the shutter the arm 16 of the shutter almost wholly closes the air conduit 14, allowing only a small quantity of air to enter in order to enable a feeble atomization or evaporation of fuel to take place in the head 10 of the fuel nozzle. In a similar manner any leaks in the support of the shutter axle 15 will allow some air to enter even if the arm 16 covers the entrance of the conduit 14. In the position of the parts shown in Fig. 5 the suction acts through the jet nozzle directly on the fuel in the compartment 2, and a vigorous jet of fuel and air mixture issues from the mouth 4 of the jet nozzle, which is then atomized completely by the ejector action of the strong air current entering the passage 5.

The tickler 17 merely aids in starting the formation of the mixture without influencing the main operation of the carburetor by merely raising the quantity of fuel entering the nozzle when starting.

The supplementary air entering the conduit 14 is not compressed, but merely sucked in through the head 10 of the fuel nozzle, so that this carburetor does not require a partial vacuum in the suction conduit, but only in the fuel nozzle head 10, outside of the jet nozzle. The

partial vacuum in this head is created by the speed at which the air enters through the conduit 14 and the jet nozzle.

The particular arrangement of the fuel evaporating nozzle 11 in an inclined position relative to the suction passage in the jet nozzle and the accommodation of all these parts in the cover 3 without the aid of any movable parts offer the advantage of altogether securing the sensitive system of nozzles against any disturbance from without. The fuel tank, in whose cover the fuel nozzle is arranged, forms a self-contained unit which is mounted in the casing for ready insertion and withdrawal, being merely heldv therein by the ring 21 which encircles the filter 22.

I wish itto be understood that I do not desire to be limited to the details described in the foregoing specification and illustrated in the drawings for obvious modifications will occur to a person skilled in the art.

I claim:

I et carburetor comprising in combination, a carburetor casing, an air opening and a mixture passage in the easing wall, a jet nozzle located in said casing with its mouth facing said mixture passage, a rocking shutter, formed With an opening of about the size of the mixture passage cross-section, being pivoted in said casing for rocking motion between the mouth of said jet nozzle and said mixture passage, a throttling member fixed in said casing near and underneath the mouth of said jet nozzle and spaced sufficiently from the casing wall to allow said shutter to move between said wall and said throttling member, a supplemental air supply conduit communicating with said jet nozzle, and a fuel conduit communicat ing with said air supply conduit and raising fuel into said jet nozzle in proportion to the quantity of air passing through said nozzle, said shutter governing the entrance of air into said supplemental air supply conduit and the issue of the quantity of fuel and air mixture from said jet nozzle into said mixture passage.

References Cited in the file of this patent UNITED STATES PATENTS 

